Sleeper accommodations in transportation are a well-known concept. They have been widely used on passenger trains, on ships, and also on aircraft. Achieving a satisfactory approach to convert airliner seats to sleeper bunks is complicated by safety considerations and the need for a lightweight, sturdy and high density configuration. In almost all prior art the passengers are facing forward or aft in both seated and prone positions. This arrangement requires every passenger to be next to an aisle or else some passengers must either wake-up or crawl over adjacent passengers to get to an aisle. One exception is Brauer, U.S. Pat. No. 6,000,659, which discloses a complicated and heavy approach of rotating side by side seats ninety degrees. This approach is also only suitable for a two-abreast bank of seats without a bunk bed arrangement and does not provide anywhere near the passenger density required for economy class.
Another exception is Mutke, U.S. Pat. No. 4,071,210, where passengers are always facing at right angles to the direction of travel and are always stacked vertically when seated or prone.
Prior to the present invention, nothing in the art allowed for three levels of bunk beds that could convert to the normal seated arrangement which is required for a speedy evacuation in case of an emergency during takeoff or landing. There is not enough time for people to be climbing down stairs or ladders and interfering with others moving along the aisles trying to exit. However a three level bunk arrangement is required to get the stretch out distance for passengers to lie prone for economy class passenger densities.
Some other unique design considerations for airliners seats include the requirement for an open view of the cabin during takeoff and landing so that the flight attendant can see persons who get up out of their seats, which often is the first indication of a problem. As a result, seats that convert to bunk beds in closed compartments typical of train sleeper cars would not be allowable on an airliner.
Modern airliner seats also need to be designed to withstand sixteen-g crash loads, and special accommodations are required if passengers are not facing close to straight forward or aft.